Of all psychiatric diagnoses, bipolar disorder (BP) imparts the greatest risk for completed suicide in adolescence, and is associated with other negative outcomes including poor psychosocial functioning and substance abuse. Furthermore, healthcare costs for adolescents with BP exceed those for other adolescent psychiatric conditions. Treatment guidelines indicate optimal management of pediatric BP includes a combination of pharmacotherapy and psychotherapy. Yet, little is known about effective psychotherapy approaches for this population, and none expressly target suicidality. An efficacious, cost-effective psychotherapy for adolescents with BP has great potential to decrease the substantial morbidity, mortality and costs associated with this illness. Dialectical Behavior Therapy (DBT) is a skills-based psychotherapy originally developed for adults with borderline personality disorder. DBT holds promise for adolescents with BP given shared treatment targets including suicidality and psychosocial functioning. Our group's preliminary data on DBT for adolescents with BP provide strong support for the feasibility and acceptability of the treatment model, and indicate DBT is associated with improvement in targeted treatment domains including suicidality, emotional dysregulation, and depression, and these improvements are greater among adolescents receiving DBT as compared with standard of care (SOC) psychotherapy delivered at our Child and Adolescent Bipolar Services (CABS) specialty clinic. The proposed study aims to evaluate in a randomized controlled trial the efficacy of DBT + pharmacotherapy as compared with CABS SOC psychotherapy + pharmacotherapy over 2 year follow- up among adolescents (age 12-18) with BP (n=100). Primary outcome domains include suicidal events and mood symptoms. Our team includes an expert in health services cost effectiveness, enabling us to examine the cost effectiveness of DBT. Our exploratory aim is to elucidate moderators and mediators of DBT treatment response in this population. Identification of patient factors that predict response to DBT, as well as mechanisms by which DBT benefits patients, will directly inform the planful dissemination of the treatment (if shown to be effective) for those most likely to benefit. These aims are in direct accord with the NIMH Strategic Plan to prioritize research on improved treatments for mental illness; facilitate widespread use of evidence- based interventions by demonstrating cost effectiveness; and systematically study elements of personalized intervention. Furthermore, this project aligns with the mission of the National Action Alliance for Suicide Prevention Research Prioritization Task Force: to prioritize gaps in the research that will reduce the rate of suicide and suicide attempts, to target particularly high-risk groups, and to move toward uptake of evidence-based interventions for suicidality.